1888. | NEW YORK ACADEMY OF SCIENCES. 125 
brine springs, originating from beds of rock-salt in some older 
geological formation—and nota direct residuum of the sea. 
This explains the entire absence of intercalations of gypsum 
and the absence of potassium and magnesium compounds.” 
Professor Hilgard thinks it should be assigned to the creta- 
ceous, since there is ‘‘no phase of the tertiary history of the 
Gulf of Mexico that seems to admit of” the conditions required, 
viz.: the long-continued evaporation of some very large body of 
sea-water. He calls attention to the banded structure of the 
rock-salt, and remarks that the ‘‘ Stassfurt salts” belonging to 
the salt mass have long ago been washed into the general ocean. 
We would call the attention of geologists to two facts which may 
throw light on the questions: the occurrence on the island of 
bedded sandstone and of lignite. Thesandstone is exposed at the 
bottom of adeepravine about 1,500 feet from the shaft, the rock is 
of a light gray color and contains little or no calcite. It is dis- 
tinctly seen to be in place, and is weathered to a considerable 
depth beneath the surface. Atthe base of another ravine, formed 
by a rivulet cutting through the alluvium, gravel and sand, and at 
a distance of about 2,000 feet from the shaft, there is an outcrop 
of lignite.’ The latter is apparently several feet in width and of 
good quality for economic purposes. Mr. McCalla reports 
that it contains fifteen per cent of ash. Both the sandstone 
and the lignite seem to dip in such a direction (S. E.), 
as would cause them to run beneath the salt. This view 
is also confirmed by some of the borings. Indications 
of fossil plants occur in the brown coal, but at the time 
of my visit it was unfortunately impracticable to dig deeply into 
it, and I had to be content with a mere surface specimen. 
There are four other islands stretching along the coast in the- 
vicinity, but borings have failed to reveal salt on any of them. 
The mine is now worked by a system of chambers and cross- 
headings. The single shaft has reached adepth of 166 feet (in- 
cluding the sump of 6 feet). The old workings at a depth of 
90 feet have been abandoned, owing to the infiltration from 
above of water carrying with it clay and sand, which rendered 
the salt impure. The lower level isat adepth of 160 feet. The 
extent of the excavation in the upper level is about 8 acres, and 
the extreme ends of the galleries are 900 feet apart. The ex- 
cavation on the lower Jevel is much smaller. The method of 
operating is to run galleries about 6 to 8 feet high, and then to 
work upward to a height of 40 feet, leaving between the galleries 
large pillars to support the roof. The boring is done with a kind 
of auger of a German pattern, imported in deference to the pre- 
judices of the workmen, who are largely Stassfurt miners. The 
auger is worked by hand and penetrates the salt one inch for- 
